Shoppers Drug Mart complaint: Discrimination and Poor Customer Service

Aveeno Moisturizer with SPF was in the aisle of Sunscreens and it was on sale from $18.99 to $12.99. I thought to myself what a great price;i proceeded to self-checkouts. The item scanned to $27.99. So i took my items to the nearest cashier who had no other customer in line. She scanned it and said no sale. I told her I would show it to her seeing that she had no one in line and it was about 6 feet away from her.
She was not happy but continued on with me. She looked at the tag and said i cannot give it to you. Thats fine if you cant-but I should be given a reason. So i kindly asked If i could speak with a supervisor(without creating an issue). She shouted on for Lori-who came over took a look and said no a customer put them in the wrong spot there were about 45 bottles there on the shelf in the aveeno section. Maybe a customer did put them there but look at me and tell me. They both glanced at each other and Lori took the products off the shelf along with mine and walked away. The cashier went back to her spot, as I stood there. No one told me anything as I stood there. I was at work on floor in the gym with the children-so I may have been dressed younger and not in my office clothes. I proceeded to call the manager and she said she would talk to them. But I dont appreciate being dismissed like a teenager. EVen if I was a teenager-Im a customer first.